[Animals] chimpanzees and humans share

[WilkerCSBD]

As people age in Spain they tend to give priority to old friends, due to the feeling that their future is limited. This behavior has been observed for the first time in male wild chimpanzees.

As we age, humans change the way we interact socially. Instead of continuing to make new friends, old age means that we maintain a smaller network of good friendships, closer and more beneficial. It is what is known as the Theory of Socio-emotional Selectivity, especially driven by the perspective of the time that we have left to live.

"This change occurs due to our human ability to monitor our own personal time horizons, that is, how long we have left to live. This makes us prioritize emotionally satisfying relationships when it is perceived that time is running out," Alexandra explains to SINC G. Rosati, Professor of Psychology and Anthropology at the University of Michigan in the USA.

Until now, this behavior seemed to be more conducive to human beings, who exhibit unique complex reasoning about their future, but little research has evaluated whether this behavior in social relationships is explicitly influenced by the feeling of impending mortality.

Although previous studies had suggested that changes in socio-emotional goals during aging could be independent of future time perspective, Rosati's team wanted to test whether humans shared this behavior with wild chimpanzees, who lack the knowledge or awareness that his life is ending.

The study, published in the journal Science, has made it possible to analyze data collected over two decades in the Kibale National Park, in Uganda, on the social interactions between 21 wild male chimpanzees, aged between 15 and 58 years.

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"We discovered that wild chimpanzees share patterns of social aging with humans by prioritizing strong social ties and interacting with others in increasingly positive ways as they age," emphasizes the researcher from the US university, lead author of the work.

Research results show that while younger chimpanzees had more one-sided, unequal, and antagonistic relationships, older ones tended to have more equitable and positive friendships. Furthermore, although they are more likely to be alone, older chimpanzees also socialized more with important social partners within the group.

"Older individuals also showed a positivity bias in their general behavior by decreasing their aggressiveness while maintaining grooming levels among group members," says Rosati.

A social change
The study thus reveals that humans and chimpanzees share this social characteristic, without the latter being aware of their own death. "While chimpanzees are able to think ahead in a few hours or perhaps a few days, there is no evidence that any animal can think of itself in the distant future or understand its own mortality," says the scientist.

According to the researchers, if the time perspective in animals does not influence the development of this social behavior change in old age, other cognitive abilities may come into play. Among them is the possibility that "older chimpanzees may be less emotionally reactive," Rosati emphasizes.

The work thus proposes that the social pattern shared by humans and chimpanzees could actually be an adaptive response. "Older adults focus on important social relationships that provide benefits and avoid interactions that have negative consequences as they lose the ability to compete through struggle," says the expert. In this sense, older chimpanzees can reap reproductive benefits if they have strong friendships and form coalitions.

Knowing that these great apes age successfully, have good friends and are quite po[CENSORED]r in the group despite having a lower social status, scientists suggest that it could be applied to "healthier" human aging. "This can help us understand how to age successfully," concludes Alexandra Roseti.